Constant changes to Firefox's user interface

Some of the new user interface and theme changes in Firefox are baffling. A few that come to mind that fall into this camp are: 1. New Download Manager with reduced functionality 2. Removal of site-icons in the address bar 3. Return of the "secure" padlock and removal of the clear "Identity Block" in the address bar We just went through a visual refresh with Firefox 4, which took a long time to develop. A lot of the decisions on what should go in that release were made after long discussions. Those discussions and decisions are being revisited and revised. Some of the behavior is being reverted back to pre-ff 4.0 days. Other, not so ideal, behavior is being introduced. Thinking about user interfaces some more, an application needs to be agile and respond to serious usability issues. But, it needs to stay true to its core look and feel. These changes, trivial when considered in isolation but significant when considered as a whole, impact the overall usability of Firefox. There is going to be a transition cost for these changes, and some of them violate the principle of least surprise[1]. The Australis theme refresh is a good example of the point I am trying to underscore. Was the theme refresh in 4.0 mostly a stop-gap measure? If yes, why introduce it in the first place? This constant back-and-forth points to a lack of UX and design leadership at Mozilla, which will result in more defections if not reined in. For a point of reference on how to manage changes to an application's interface without deviating too far from the original design principles, look no further than Google Chrome. It pains me to say this, but the original designers of that application had their sights set far into the future. Changes to its interface are subtle and rarely jarring. [1]: The Principle of Least Surprise